Update app.py

app.py

@@ -2165,7 +2165,7 @@ def similarity_matching(sprites_data: str, project_folder: str) -> str:
     #  Copy matched backdrop assets + collect
     # =========================================
     backdrop_data = []
-
+    copied_backdrop_folders = set()
     for backdrop_idx, matched_idx in enumerate(most_similar_indices):
         matched_image_path = folder_image_paths[matched_idx]
         matched_folder     = os.path.dirname(matched_image_path)
@@ -2175,6 +2175,11 @@ def similarity_matching(sprites_data: str, project_folder: str) -> str:
         if not matched_folder.startswith(backdrop_base_path):
             continue
 
+        # skip if backdrop folder already processed
+        if matched_folder in copied_backdrop_folders:
+            continue
+        copied_backdrop_folders.add(matched_folder)
+
         logger.info(f"Matched backdrop: {matched_image_path}")
 
         # 1) Copy the matched backdrop image itself